The HarmonicAngle interaction implements a potential that depends quadratically on the bend angle $\theta$ , with a minimimum at some angle $\theta_{0}$ . The energy is given by

$V(\theta) = \frac{\kappa}{2} ( \theta - \theta_0 )^{2}$

Different values are defined for the parameters $\kappa$ and $\theta_{0}$ for each angle type.

Values of the parameters $\kappa$ , $\theta_0$ are denoted in the parameter file and source code by array-valued variables named "kappa", and "\theta_0", respectively.

The parameter file format is:

kappa Array<float>

theta0 Array<float>

Values of kappa are entered in energy per square radian. Values of theta_ are are entered into the parameter file in degrees, but these values are immediately converted into radians. Radian units are used for all internal calculations.

Both arrays are entered in column form, with one entry per line, with the first entry after the label. The parameter block for a system with two angle types (nAngleType=2) might thus look like:

kappa     50.0
          40.0
sigma     60.00
          30.00